DISEASES OF THE OX AND SHEEP. 469 



A tapeworm may be said to be a cestode form of a colony of 

 zooids arranged in single file, the topmost zooid being the so- 

 called head or nurse. The worm may take three months to arrive 

 at its full size, and at about that age the Tmnia mediocanellata 

 consists of as many as 1,200 zooids joined together. When this 

 number is attained, the last zooid falls off, then the next, and so 

 on, about eight of them being expelled with the feces each day 

 that comes. A person infested by one of these tapeworms passes 

 1,200 zooids four times in each year. Now, each zooid contains 

 35,000 eggs, and hence 168 million eggs are distributed in one 

 year. We need not, then, be very much surprised to hear that 

 in one case a single pound of psoas muscle taken from a beast 

 in India was found to contain 300 larval forms, and conse- 

 quently we shall observe that beef as well as pork should always 

 be most thoroughly cooked. 



We now proceed to consider those Cestodes which have been 

 found in young ruminants. There are not many tapeworms 

 which are known to infest ruminants. Cattle are liable to har- 

 bour the Tania expansa, and also the Tcenia denticulata, the 

 former of which is more or less prevalent in sheep, antelopes, and 

 deer. Large numbers of lambs perish as a result of the presence 

 of tapeworms {Tania expafisa), and the loss in Australia from 

 this cause is especially great. 



The latter occurs also in the ox, gazelle, chamois, and other 

 animals. It seems that this tapeworm frequently attacks sheep 

 which are kept on overstocked land, and for this reason, as well 

 as for many others, it is advisable that only a sufficient number 

 of these animals should be kept together. The head of this 

 tapeworm, the T(Enia expansa^ is unarmed and provided with four 

 suckers. The animal is made up of the enormous number of 

 7,000 segments which are broader than they are long. Each 

 segment is provided with two reproductive papillae on either side, 

 and each is a double hermaphrodite. These tapeworms, in the 

 case of the ox, have been known to measure as much as 100 ft. 

 in length, but they are usually about 40 or 50 ft. long. In 

 lambs they vary in length from 1 to about 7 or 8 ft. in length. 

 They infest the intestinal canal. 



As yet the source and life-history of these tapeworms do not 

 appear to have been determined, but possibly the larvae may 

 exist in the ox-louse or in some other insect, for it may be taken 



